Tips for monsoon conditions

It didn’t rain a drop in the Phoenix area in June, which isn’t unusual.

June traditionally is one of the driest months of the year for the Valley, even though the annual monsoon officially began on June 15. The month averages about 0.04 inches of rain annually.

But don’t worry, the summer “rainy” season is on the way. It’s just taking a while.

July marks the beginning of a period that traditionally has delivered metro Phoenix residents their first taste of the summer monsoon. July has traditionally been one of the rainiest months, averaging a little more than an inch annually. (Remember, Phoenix is in a desert and averages only about 8 inches for the entire year.)

Here comes the humidity

That means higher humidity, which helps keep temperatures from soaring beyond 110 degrees, along with cloud buildups, lightning shows, wind, dust storms and, eventually, rain.

Signs of the impending monsoon will be incremental over the course of the next week, according to the National Weather Service.

The Phoenix NWS said there is a 10 percent chance of rain on Thursday in the Valley and a 20 percent chance on Friday.

By early next week, that probability will rise to 30 percent, NWS officials aid.

“In the Sonoran Desert (to the south), low pressure forms, and high pressure forms around the Four Corners (in northeast Arizona),” said Bianca Hernandez, an NWS meteorologist. “The flow around the high and low pressure ends up advecting moisture.”

In other words, heat that builds up during the day combines with moisture being drawn up from Mexico to create the summer storms that usually show up late in the afternoon and early evening.

Hernandez explained that the pressure coming south from Mexico and north from the Four Corners will then hang around Arizona for a couple of months, creating a seasonal storm pattern — Arizona’s summer monsoon.

“Once we get that pattern, there will be days where it’s active and days where it’s less active,” Hernandez said.

Signs of the monsoon’s activity already have occurred in southeastern Arizona and along the Mogollon Rim, areas that have seen thunderstorm activity in recent days.

The chances for rain in the Phoenix area will recede later next week before picking up again.

In the event of a rainstorm, Hernandez cautioned people to be aware of possible flooding, stay off closed roads and keep a safety kit in their car, in case they are stuck inside their vehicle.

In a dust storm, Hernandez said people should park their cars when it’s too difficult to see, and turn off their lights when pulling off to the side of the road. That helps prevent drivers who are behind in poor visibility from mistakenly thinking that you are continuing in traffic, following you and then failing to stop in time.

Hernandez also said that even though it’s the monsoon, residents still need to be wary of extreme heat that will stick around.

Thursday’s predicted high is 113, and Friday’s is 114.